refactor: port backend and frontend to TypeScript classes (bun + vite)

Backend (src/server, runs on Bun):
- GibbzHttpServer (health, /api/ice, /api/rooms, static, keepalive tuning)
- SignalingServer with Peer/Room/RoomRegistry classes and typed messages
- IceConfigProvider (env STUN/TURN + coturn HMAC ephemeral creds)
- StaticFileServer (dist/ with public/ fallback, traversal guard)
- Tracing (OpenTelemetry SDK), AppConfig; createApp() factory for tests

Frontend (src/client, built by Vite):
- VoiceApp orchestrator implementing VoiceAppContext
- WebRtcManager + PeerSession (perfect negotiation, pc rebuild, quality monitor)
- SignalingClient + ReconnectController, AudioManager, SpatialAudio,
  Microphone/ScreenShare controllers, ScreensUi/RosterUi/SpatialMap/
  SpeakingMonitor, Settings/Welcome dialogs, LayoutManager, MatrixChat

Tooling: bun scripts (dev/start/test/typecheck), vite.config.ts root
src/client with publicDir public/static, vitest-config for CI-less runs,
bun-based Dockerfile (oven/bun:1), Makefile + README updated, legacy
server.js/tracing.js/test.js/public js removed.

Verified locally: tsc --noEmit clean, vitest run 6/6 green, vite build ok,
server smoke-tested serving dist + signaling endpoints under Node. Local
bun binary segfaults (SIGILL) on this host, so 'bun test' itself was not
executable here; tests are vitest-API compatible which bun test maps.

src/server/config.ts

@@ -0,0 +1,21 @@
+import fs from 'node:fs';
+import path from 'node:path';
+
+/**
+ * Runtime configuration resolved from the environment.
+ *
+ * The static directory prefers the Vite production build (`dist/`) and falls
+ * back to `public/` so a dev-mode server never 404s outright.
+ */
+export class AppConfig {
+  readonly port: number;
+  readonly host: string;
+  readonly staticDir: string;
+
+  constructor(env: Record<string, string | undefined> = process.env, cwd: string = process.cwd()) {
+    this.port = Number(env.PORT || 8080);
+    this.host = env.HOST || '0.0.0.0';
+    const dist = path.join(cwd, 'dist');
+    this.staticDir = fs.existsSync(dist) ? dist : path.join(cwd, 'public');
+  }
+}